Florian Lejeune will miss the remainder of the season after being carried off in the game at Crystal Palace at St James' Park.
As reported on Chronicle Live on Sunday, the club's medics feared Lejeune's season was as good as over after he suffered knee damage after a challenge with Andros Townsend.
But the centre-back is tipped to make a complete recovery and be back in contention for next season.
A United statement read: " Newcastle United can confirm defender Florian Lejeune sustained a significant knee injury during Saturday’s game against Crystal Palace.
"The 27-year-old was forced off on a stretcher during the second half at St James’ Park after injuring his left knee – not the knee injured during pre-season which saw him miss the start of the campaign.
" Lejeune has been ruled out for the remainder of the current season and further updates on his recovery will be provided in due course.
"The Frenchman had been ever-present for the Magpies in the Premier League since his return to action at the start of January, taking his 2018/19 tally to 13 appearances in all competitions."
Benitez had said: "He said he felt a click in his knee, so that is bad news normally."
Rafa Benitez says the door is STILL open at Newcastle United for Dwight Gayle and Jacob Murphy
Rafa Benitez pinpoints his biggest frustration after Newcastle United's defeat to Crystal Palace
